U.S. patent number 4,522,962 [Application Number 06/185,253] was granted by the patent office on 1985-06-11 for epoxy modified emulsion polymers.
This patent grant is currently assigned to SCM Corporation. Invention is credited to Kirk J. Abbey, James R. Erickson.
United States Patent |
4,522,962 |
Abbey , et al. |
June 11, 1985 |
Epoxy modified emulsion polymers
Abstract
Emulsion polymers produced by polymerizing ethylenically
unsaturated monomers in an aqueous medium can be substantially
improved by incorporating into the monomer mixture a minor amount
of blend of epoxy resin and glycidyl acrylate. The epoxy modified
emulsion polymers are particularly useful as ambient or low
temperature thermosetting latices for film-forming coatings.
Inventors: |
Abbey; Kirk J. (Cleveland,
OH), Erickson; James R. (Brunswick, OH) |
Assignee: |
SCM Corporation (New York,
NY)
|
Family
ID: |
22680231 |
Appl.
No.: |
06/185,253 |
Filed: |
September 8, 1980 |
Current U.S.
Class: |
523/410; 523/404;
525/117; 525/529; 525/530; 528/103 |
Current CPC
Class: |
C08F
2/22 (20130101); C09D 151/08 (20130101); C08F
283/10 (20130101) |
Current International
Class: |
C08F
2/12 (20060101); C08F 2/22 (20060101); C08F
283/00 (20060101); C08F 283/10 (20060101); C09D
151/08 (20060101); C08G 059/00 (); C08K
003/20 () |
Field of
Search: |
;260/29.6NR,29.6PM,29.2EP ;525/529,117,530 ;528/103
;523/410,404 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
112959 |
|
Sep 1979 |
|
JP |
|
1384435 |
|
Feb 1975 |
|
GB |
|
1433064 |
|
Apr 1976 |
|
GB |
|
2046767 |
|
Nov 1980 |
|
GB |
|
Other References
Derwent Abst. 76556W/46 (J50097698) Mitsubishi Electric (8-2-75).
.
Derwent Abst. 79609W/48, Nippon Oil KK (J75034076), 11-5-75. .
Derwent Abst. 53082W/32, Shimokawa (J50040642) 4-14-75..
|
Primary Examiner: Lilling; Herbert J.
Attorney, Agent or Firm: Schmitz; Thomas M.
Claims
We claim:
1. In an emulsion polymerization process the improvement comprising
the steps of:
providing a blend comprising on a weight basis, between 0.1% and
40% of an epoxy resin polymer, between 30% and 99.8% ethylenically
unsaturated monomers, and between 0.1% and 30% oxirane containing
ethylenically unsaturated monomers, and polymerizing said blend in
an aqueous medium in the presence of polymerization catalysts to
copolymerize said ethylenically unsaturated monomers with said
oxirane containing ethylenically unsaturated monomers to form an
oxirane polymer and provide an in situ emulsified blend of oxirane
polymer and said epoxy resin polymer.
2. The composition in claim 1 wherein the oxirane monomer contains
a pendant double bond and is a derivative of glycidol.
3. The composition in claim 1 wherein the oxirane monomer is
selected from an acrylic, a methacrylic, or a vinyl derivative of
glycidol.
4. The composition in claim 1 wherein the oxirane monomer is
selected from glycidyl acrylate, glycidyl methacrylate, or allyl
glycidyl ether.
5. The composition in claim 1 wherein the epoxy resin is a linear
polymer.
6. The composition in claim 1 wherein the composition contains a
multi-functional amino or mercapto cross-linker adapted to
cross-link said polymer.
7. A coating composition containing the polymer composition in
claim 1 wherein the coating is curable to provide a protective
surface coating.
8. A coating composition in claim 1 wherein the composition
contains an amine or mercaptan cross-linker for cross-linking the
coating upon curing.
Description
BACKGROUND OF THE INVENTION
This invention pertains to emulsion polymerization of ethylenically
unsaturated monomers in an aqueous medium and particularly to epoxy
modified emulsion polymers.
Epoxy modified polymers are shown in U.S. Pat. No. 4,028,294
wherein epoxy resins described as polyepoxides of dihydric phenols
such as bisphenols are blended with acrylic monomers and emulsion
polymerized to provide thermosetting latex particles. Similarly,
U.S. Pat. No. 3,970,628 discloses emulsion polymerized monomers
containing epoxy resins.
It now has been found that substantially improved epoxy modified
emulsion polymers can be produced by providing an epoxy blend of
epoxy resin with glycidyl acrylate, glycidyl methacrylate or other
oxirane containing ethylenic monomer. This epoxy blend can be
produced by including the epoxy resin in the emulsion reaction
medium by dissolving the epoxy resin in ethylenically unsaturated
monomers prior to being added to the aqueous medium or by adding
the epoxy resin simultaneously with the ethylenically unsaturated
monomer as a separate pre-emulsified portion. The epoxy modified
emulsion polymers of this invention provide substantially improved
latices suitable for use as ambient or low temperature
thermosetting film-forming binder for protective coatings. The
cured coating exhibit improved salt spray resistance, solvent
resistance, impact resistance as well as other desirable cured film
integrity properties. These and other advantages will become more
apparent by referring to the detailed Description of the
Invention.
SUMMARY OF THE INVENTION
Briefly, an emulsion polymerization process is directed to
copolymerizing ethylenic monomers with glycidyl acrylate or
methacrylate or other oxirane monomer in the presence of moderate
amounts of epoxy resin. The epoxy resin is mixed with the monomers
prior to the addition of monomers to the reaction medium or added
simultaneously with the monomers. The latex is particularly
suitable for binders for protective coatings adapted to cure at
room temperatures or low temperatures above room temperature.
DETAILED DESCRIPTION OF THE INVENTION
The process of this invention pertains to emulsion copolymerization
of ethylenic monomers and oxirane monomers in the presence of epoxy
resin to produce emulsion latex polymer particles containing
oxirane groups in combination with epoxy resin containing epoxide
groups. The ethylenic monomers, oxirane monomers, and epoxy resin
can be either intermixed together prior to the emulsion
polymerization process or the epoxy resin preferably can be
separately emulsified. An important aspect of this process is that
the epoxy resin is available during the free radical polymerization
so as to yield an intimate blend. Other advantages such as chain
transfer to the epoxy resin is believed to occur. Conventional
aqueous emulsion polymerization is utilized at temperatures between
about 45.degree. C. and 95.degree. C. in the presence of free
radical initiators or polymerization catalysts.
Referring first to the monomers, the oxirane monomers
characteristically contain oxirane functionality ##STR1## as well
as pendant ethylenic double bond unsaturation and includes, for
example, acrylic, methacrylic, or vinyl derivatives of glycidol.
Preferred oxirane monomers contain pendant oxirane and include
glycidyl acrylate, glycidyl methacrylate, and allyl glycidyl ether.
The oxirane monomers can be copolymerized with ethylenically
unsaturated monomers which include, for example, vinyl aromatic and
aliphatic hydrocarbons such as styrene, alpha-methyl styrene and
similar substituted styrenes, vinyl naphthalene, vinyl toluene,
divinyl benzene, and vinyl aliphatic hydrocarbons such as
1,3-butadiene, methyl-2-butadiene, 2,3-dimethyl butadiene,
cyclopentadiene and dicyclopentadiene as well as ethylenically
unsaturated esters and acids such as acrylic, methacrylic,
ethacrylic, cinnamic and crotonic and the like and esters
containing fumaric and maleic type unsaturation. Particularly
preferred monomers include, for example, styrene, alpha-methyl
styrene, tertiary butyl styrene, divinyl benzene, 1,3-butadiene,
isoprene, alkyl acrylates such as ethyl acrylate, butyl acrylate,
methyl-methacrylate, acrylonitrile, vinyl acrylate, and vinyl
methacrylate as well as similar ethylenically unsaturated monomers.
The monomer mixture on a weight basis can contain between 0.2% and
30% oxirane monomer and between 99.8% and 70% ethylenically
unsaturated monomers.
The epoxy resin is a lower molecular weight epoxy resin
characterized by the epoxy group ##STR2## and can be represented by
aromatic resins such as bisphenols reacted with epichlorohydrin,
cycloaliphatic resins such as hydrogenated bisphenol based epoxy
resins, and partially epoxidized vegetable oils. The epoxy can be a
linear epoxy polymer chain although side chain adducts can be
produced by coreacting epichlorohydrin with other dihydric phenols
or polyhydric phenols, polyalcohols, and polyfunctional
halohydrins. Epichlorohydrin and dichlorohydrin are preferred
reactants with phenols to provide pendant epoxy groups. The epoxy
resin should have an epoxide equivalent weight between 65 and 1800,
and a molecular weight between about 100 and 4000. The epoxy resin
can be illustrated as: ##STR3## The preferred epoxy resin is a
linear polymer chain having n repeating units of epichlorhydrin
adducts of various bisphenols such as bisphenol-A, bisphenol-S,
etc., wherein n can be between 0 and 4 and said epoxy resin is
fluid or can be dispersed within the mixture of ethylenic and
oxirane monomers and emulsion polymerized in accordance with the
invention. The monomer and epoxy resin mixture can contain on a
weight basis between about 0.1% and 30% ethylenically unsaturated
oxirane monomer, 99.8% and 30% ethylenically unsaturated monomer,
and 0.1% and 40% epoxy resin.
The monomer and epoxy resin mixture can be added initially or
continuously or intermittently to an aqueous reaction medium over a
period of 1 to 10 hours at temperatures between about 45.degree. C.
and 95.degree. C. in the presence of initiators, surfactants, and
emulsifiers. The polymerization catalyst or initiator can be one or
more water soluble, free radical generating species such as
hydrogen peroxide or the sodium, potassium or ammonium persulfate,
perborates, peracetates, percarbonate, and the like. As is well
known in the art, these initiators may be activated by a redox
system such as sulfites and thiosulfites and redox promoters such
as transition metal ions. Those skilled in the art will be aware
that other polymerization initiators such as relatively water
insoluble organic peroxides may also be used when compatible with
the polymerization system herein employed. Other initiators are
benzoyl peroxide, acetyl peroxide, lauryl peroxide, acetone
peroxide, cumene hydroperoxide, and the like, as well as
azobisisobutylnitrile and similar azo-compounds. The initiator is
normally used in amounts between 0.1 and 2 weight percent based on
monomer.
Suitable surfactants include anionic, nonionic and cationic
emulsifiers. Examples of anionic surfactants include alkyl
carboxylic acid salts, the alkyl sulfate salts, the alkyl sulfonate
salts, the alkyl phosphate salts, the alkyl sulfo-succinate salts,
the oligomeric and/or polymeric carboxylic acid salts, the alkyl
aryl ether alcohols and the alkyl aryl polyether sulfate salts.
Catonic emulsifiers include the alkyl imidazoline salts, the
quarternary ammonium salts including one or two long alkyl chains,
the alkyl pyridinium salts, the oligomeric and/or polymeric amine
salts, and the alkyl aryl ammonium salts. Nonionic surfactants
include ethylene oxide adducts of fatty alcohols or of alkyl
phenols or naphthols, and the block copolymer of ethylene oxide and
propylene oxide. Mixtures of surfactants can be utilized including
nonionic surfactants admixed with either anionic or cationic
surfactants. Surfactants are ordinarily used at the level of 0.06%
to 6% by weight based on monomers.
The emulsion latex containing an in-situ intermixture of epoxy
resin contains two types of oxirane reactivity, that is oxirane
resin and oxirane containing ethlenically unsaturated monomer,
which has been found to be ditinctly better than either moiety
alone. The in-situ polymerization resulted in superior properties
than achieved by a mechanical blend. The latices can be
advantageously cured at ambient temperatures or close to room
temperature, as well as at higher temperatures.
In use, the oxirane emulsion polymer containing epoxy resin can be
cured in accordance with this invention by curing agents such as
polyamines including amidoamines, oligomers of ethylene imine,
amine functional acrylic resin and the like. Polymercaptans
likewise are useful. Lesser preferred acidic or basic curing agents
can be used but these often require moderate heat. The weight
percent curing agent to be used is controlled, as is known in the
art, by the oxirane equivalency of the oxirane emulsion polymer and
the amine equivalency of the curing agent (or thiol equivalency,
etc.). The ratio or these two values can be between about 1:3 and
3:1 and most preferably nearer to 1:1 equivalent of amine to
oxirane, although wider ranges such as 10/1 can be used.
The merits of this invention are further illustrated in the
following examples.
EXAMPLE 1
In accordance with the process of this invention, the epoxy resin
is dissolved within the ethylenic monomers and reacted
simultaneously.
______________________________________ Component Wt. parts
______________________________________ A. Deionized water 115.96
Polywet KX-4 (Uniroyal) 0.54 B. K.sub.2 S.sub.2 O.sub.8 0.30 C.
Butyl acrylate (BA) 55.71 Methyl methacrylate (MMA) 44.84 Glycidyl
acrylate (GA) 2.00 Epon 828 (Shell) 15.73 D. Deionized water 0.10
Sodium formaldehyde sulfoxylate 0.01 (A.W.C. Rice, Diamond
Shamrock) ______________________________________
Procedure:
(1) Charge A and heat to 83.degree. C. with a nitrogen sparge.
(2) After 30 minutes change the nitrogen sparge to a blanket.
(3) Charge 3% of C and mix for 3 minutes.
(4) Charge B and allow to polymerize for 5 minutes.
(5) Feed the remainder of C over a 3-hour period.
(6) Add D after completing the monomer feed and hold for 1
hour.
(7) Cool and filter.
EXAMPLE 2
Latices were produced according to the process in Example 1, except
that the components in Group C were follows:
______________________________________ Component Wt. (a) Wt. (b)
______________________________________ C. Butyl Acrylate 47.57
57.26 Methyl Methacrylate 42.21 45.34 Glycidyl Acrylate 12.50 0
Epon 828 0 18.73 ______________________________________
Table I hereinafter presents test data for the above latices cured
with 1,6-hexanediamine at room temperatures of about 20.degree. C.
to 25.degree. C. and at low bake of about 75.degree. C. The amount
of diamine used was such that 1.25 amine nitrogens were available
per oxirane moiety. For comparison, mechanical blends of glycidyl
acrylate latices plus DER 331 (Dow) emulsions are similarly
prepared and cured. The data shows that the mixture of oxirane
source is better than either moiety singly, and further, that the
in-situ mixture is better than the subsequently mechanically
blended mixtures.
TABLE I
__________________________________________________________________________
Responses After Cure With 1,6-Hexanediamine Oxirane
Distribution.sup.a Salt Spray.sup.c Solvent Resistance.sup.d
Reverse Impact.sup.e Gel Content (%).sup.f Monomer/Resin Actual
Oxirane.sup.b 25.degree./75.degree. C. 25.degree./75.degree. C.
25.degree./75.degree. 25.degree./75.degree . C.
__________________________________________________________________________
Example 1 .16/.67 .82 4.0/7.1 >200/>200 >160/>160 36/53
Comp. Ex. 2a .95/0 .79 0/0 62/>200 50/<10 75/87 Comp. Ex. 2b
0/.80 .78 0/7.0 0/27 >160/>160 3/3 Blend 1 0/.79 .79 0/6.9
37/38 >160/>160 30/37 Blend 2 .16/.67 .79 0/7.2 86/144
>160/>160 55/-- Blend 3 .40/.48 .76 0/0 139/>200
>160/>160 64/68
__________________________________________________________________________
.sup.a Theoretical milliequivalents per gram solids based on
starting materials. .sup.b Experimentally determined
milliequivalents per gram solids by titration. .sup.c Evaluated
after aging 10 days on ironphosphated cold rolled steel; 0 -- total
failure, 8 -- no failure. .sup.d Double rubs with a rag soaked with
methyl ethyl ketone. .sup.e 5/8 inch ball; expressed as inch
pounds. .sup.f After 3 days in acetone as solvent. Note Comparative
Example 2a ha a gel content of 80% before diamine was added.
EXAMPLE 3
These examples and comparative examples vary somewhat in the type
and amount of ingredients relative to Example 1, but the procedure
is significantly different. The procedure herein described is
desirable since the reactor is slightly cleaner at the end of the
reaction. Table II presents recipes and the procedure follows.
Table III presents salt spray evaluations.
TABLE II ______________________________________ Ingredients (c) (d)
(e) (f) ______________________________________ A DI. H.sub.2 O
103.74 103.74 109.74 109.74 (surfactant KX-4 0.70 0.70 0.70 0.70
and NaHCO.sub.3 0.374 0.374 -- -- buffer NaOH 0.127 0.127 -- -- B
K.sub.2 S.sub.2 O.sub.8 0.40 0.40 0.40 0.40 (initiator) D.I.
H.sub.2 O 12.00 12.00 12.00 12.00 C BA 46.36 31.94 46.36 31.94
(first MMA 41.14 25.98 41.14 25.98 stage GA 12.50 1.407 12.50 1.407
monomer Epon 828 -- 15.67 -- 15.67 feed) CHCl.sub.3 0.50 0.352 --
-- B' K.sub.2 S.sub.2 O.sub.8 0.20 0.70 -- -- (initiator) D.I.
H.sub.2 O 6.00 6.00 -- -- C' BA -- 13.46 -- 13.46 (second MMA --
10.95 -- 10.95 stage GA -- 0.593 -- 0.593 monomer CHCl.sub.3 --
0.148 -- -- feed) D A.W.C. Rice 0.01 0.01 0.01 0.01 (reductant)
D.I. H.sub.2 O 0.10 0.10 0.10 0.10 E Super Ad-It 0.10 0.10 0.10
0.10 (fungicide) (Tenneco Chemicals)
______________________________________
Procedure for Example 3.
1. Change A to Morton flask equipped with paddle stirrer,
condenser, and thermometer; heat to 83.degree. C. bath temperature;
sparge with N.sub.2.
2. Remove sparge but continue N.sub.2 blanket; charge 3% of
monomers (C+C') and mix for 3 minutes.
3. Charge B, stir for 5 minutes, and start feed (C).
4. Meter C (and C') over 3 hours
5. Charge B' at midpoint of feed period.
6. When C (and C') is all in, charge D; hold for 1 hour.
7. Cool to 30.degree. C. or less.
8. Add E dispersed in a small amount of water, dropwise with
stirring.
9. Filter (100 mesh screen) and store.
Paints were prepared using these latices substituted into a
propriatory formulation and evaluated both with and without the
curing agent 1,6-hexanediamine.
TABLE III ______________________________________ Salt Spray
Performance Without Curing Agent With Curing Agent 240 hours 672
hours 240 hours 672 hours Sample Rating Rating Rating Rating
______________________________________ Comp. (c) 0.5 0 9.0 0.5
Exam. (d) 2.5 0 9.5 5.5 Comp. (e) 6.0 0.5 9.0 0.5 Exam. (f) 0.5 0
8.5 7.0 Propriatory 9.0 8.5 9.5 0.5
______________________________________
The paint films were evaluated over cleaned cold rolled steel
panels after the paint films were cured at room temperatures for 1
week.
Test Rating: 0=total failure; 10=excellent panel
EXAMPLE 4
The procedure of this example differs considerably from the
previous examples. Herein the epoxy resin was added separately but
concurrent to the ethylenically unsaturated monomers as an
emulsion, which had been previously prepared. At the end of the
reaction the resultant polymer dispersion was found to filter much
more cleanly than the other examples and the reactor contained no
adherent resin.
Table IV give the recipe for the epoxy resin pre-emulsion and the
procedure follows the table. This emulsion was normally prepared 24
hours in advance but was found to still be usable at least for one
week when stored at 20.degree. C.
TABLE IV ______________________________________ Epon 828
Pre-emulsion Group Material Parts
______________________________________ A Deionized Water 100.00
Siponate DS-10 (Alcolac) 0.20 Triton X-100 (Rohm & Haas) 0.72 B
Epon 828 100.00 ______________________________________
Procedure:
(1) Prepare solution A and heat to 60.degree. C.
(2) Heat B to 60.degree. C. in a container and agitate with a
Cowles type mixer (a Premier Dispensator with a Cowles blade was
used).
(3) Add A, in portions of 10% every 3-4 minutes to B adjusting the
mixer speed as required (the mixture thickens requiring higher
speeds). (The initially formed water-in-oil emulsion will invert to
an oil-in-water emulsion during the third or fourth portion).
(4) Add remaining A slowly and continuously after the emulsion
inverts.
(5) Cool to room temperature.
A latex was prepared using this pre-emulsion according to the
recipe of Table V. The procedure follows the table.
TABLE V ______________________________________ Recipe Using Epoxy
Resin Pre-Emulsion Group Material Wt. parts
______________________________________ A Deionized H.sub.2 O 92.61
Polywet KX-4 0.54 B K.sub.2 S.sub.2 O.sub.8 0.30 Deionized H.sub.2
O 12.00 C BA 48.02 MMA 35.30 GMA (glycidyl 5.00 methacrylate) D
Pre-Emulsion 23.36 E A.W.C. Rice 0.01 Deionized H.sub.2 O 0.10 F
Super Ad-It 0.10 Deionized H.sub.2 O 1.00
______________________________________
Procedure:
(1) Heat A to 83.degree. C. under a N.sub.2 sparge.
(2) Charge 3% of C and agitate for 5 minutes.
(3) Change N.sub.2 sparge to blanket, then charge B, wait 5
minutes.
(4) Start feeding C and D simultaneously at such a rate that C
requires 3 hours and D requires 2 hours.
(5) After C has been entirely added, charge E and hold at
83.degree. C. for 1 hour.
(6) Cool to about 30.degree. C. and add F.
(7) Filter through 200 mesh screen and store.
EXAMPLES 5-11
These preparations are essentially the same as Example 4 with
recipe modifications. Table VI presents these changes.
TABLE VI
__________________________________________________________________________
Further Examples Using An Epoxy Pre-Emulsion Group Material Ex. 5
Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. 11
__________________________________________________________________________
A Deionized H.sub.2 O 92.61 88.82 88.82 88.42 83.33 83.18 88.63
Polywet KX-4 0.54 0.54 0.54 0.54 0.54 0.54 0.54 C BA 48.78 45.90
46.67 46.32 42.70 43.38 45.67 MMA 37.54 33.63 35.86 35.58 31.10
33.27 33.44 GMA 2.00 5.00 2.00 2.00 5.00 2.00 5.00 D Pre-Emulsion
Epon 828 23.36 30.94 30.94 -- -- -- -- Pre-Emulsion Eponex 1510
(Shell) -- -- -- 32.20 42.40 42.70 31.80
__________________________________________________________________________
COMPARATIVE EXAMPLES 12-14
These materials were prepared for comparative purposes and followed
Example 4 except for recipe changes presented here in Table
VII.
TABLE VII ______________________________________ Comparative
Examples Group Materials Ex. 12 Ex. 13 Ex. 14
______________________________________ A Deionized H.sub.2 O 86.29
104.53 79.53 Polywet KX-4 0.54 0.54 0.54 C BA 45.76 52.18 41.86 MMA
36.24 33.58 33.14 GMA -- 14.24 -- D Pre-Emulsion 36.00 -- -- Epon
828 Pre-Emulsion -- -- 50.00 Eponex 1510
______________________________________
The foregoing are examples illustrating the merits of this
invention but are not intended to be limiting except as defined by
the appended claims.
* * * * *